This section provides background information related to the present disclosure which is not necessarily prior art. This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
A miniature mechanical shutter for use in ultra-high vacuum (UHV) scientific experiments is provided. In many contemporary atomic physics experiments, including the production of Bose-Einstein condensates (as is our intended use), it is necessary to temporarily block a beam of hot atoms from the experimental region. Since the entire experiment takes place in a vacuum chamber, a shutter made from vacuum compatible parts is needed. Additionally, the shutter needs to be fast (on the order of a few milliseconds or less) in order to fit into typical experimental time sequences. Mechanical shutters currently available on the market are for use external to the vacuum chamber, are large and bulky, are slow or manual, or are costly.
The device provided here is entirely controlled by low-voltage electronics, fits into a space less than 2″×2″×5″, has a travel time (time from completely open to completely closed, or vice versa) of about 2 milliseconds, has a simple mechanical design, and is made of inexpensive materials. Commercially available shutters have limited size options. The shutter presented here has components that are all adaptable and can be customized for any system.
Although it can be used to block a beam of atoms, the device of the present teachings is also advantageous in connection with blocking optical beams inside a vacuum, in cases when an external shutter cannot be used.
According to the principles of the present teachings, a shutter system is provided having a stainless steel tube with a flattened middle section that has a hole in it. The housing of the shutter has two caps constructed from standard vacuum compatible components. In each cap, there is a Teflon disk that serves as a soft stop for the shutter's motion, as well as a section of glass tubing that serves as a minimal friction track on which the shutter operates. Three neodymium magnets (one in each end of the steel tube, and one external to the housing) control the rotational and axial motion of the shutter. The other components that control the axial movement of the shutter are external to the chamber. A pulse of current through a solenoid (a coil of wire) creates a magnetic field that displaces one of the magnets, causing the shutter to open or close, depending on the direction of the current. The current pulses are controlled by a H-bridge circuit in conjunction with a TTL pulse generator, both of which are external to the chamber as well. The shutter operates with current pulses at 8 volts and 5 amperes, with pulse durations of about 50 milliseconds (ms). The shutter action occurs 10 to 15 ms after pulse is initiated, and the total time of movement of the shutter is about 2 ms. For our application, the shutter will cycle once every 10 to 60 seconds, resulting in negligible heating of the solenoid. The adjustable parameters of the constructed device are the location of the solenoid in relation to the magnet, the current, the voltage, and the pulse duration. The parameters are optimized for best performance.
The device was tested both in atmosphere and vacuum, and two attributes were tested: maintenance-free operating period and failure rate. For the first, the shutter was tested in continual cycles for a few days to ensure that the parts did not fail, nor that the shutter got stuck. To find the failure rate, over 3000 periods were sampled, and each individual pulse was examined for failures (i.e., cases of partial or no movement). No failures were found for either test.
The shutter has two recovery options in case it does get stuck. First, applying a long, high current pulse would free the shutter. An alternative method is to bring another magnet close to the axial magnet to free the shutter. If the shutter needs to be disabled for experiments that do not require it, an additional magnet can be fixed to the outside of the cap to lock the shutter in either the open or closed position.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.